It is common practice in the mattress and furniture industry for bedding springs to be manufactured on a so-called coiler and fed directly from that coiler into an assembly machine whereat the springs are assembled into rows and columns and joined together to create a mattress spring core. Such a machine is described, for example, in U.S. Pat. Nos. 4,492,298 and 4,111,241.
Recently, mattresses have been designed which utilize multiple differing springs of differing firmness throughout the spring core. In some cases, springs of one firmness are used on one side of a mattress, and springs of a different firmness on the other side to accommodate two persons who prefer mattresses of differing firmness. Such a mattress is illustrated and described, for example, in U.S. Pat. No. 5,987,678. In other cases, springs of differing firmness are located around the edge of a mattress to impart a firm edge to the mattress. And, in still other cases, springs of differing firmness are located in differing longitudinal sections of the mattress to vary the firmness over the length of the mattress. These later varying firmness mattresses are identified as so-called xe2x80x9cposturizedxe2x80x9d mattresses. Such a posturized mattresses is described, for example, in U.S. Pat. No. 5,868,383.
The advent of these multiple spring mattresses has given rise to the need for machinery for manufacturing those springs of differing firmness and supplying them to an assembly machine in a predetermined order or sequence. To that end, mattress making machinery has been created which utilizes two coilers to supply two different springs to a single assembly machine in a prescribed sequence. This requires, though, that there be two coilers and a complex transport system, as well as a complex control system, for feeding springs from the two different coilers in a prescribed sequence to the mattress spring core assembly machine. Such a machine is illustrated and described, for example, in U.S. Pat. No. 5,579,810.
The machines which have been heretofore available for supplying springs of differing firmnesses to an assembly machine in a prescribed sequence or order are very expensive and complex. It has therefore been an objective of this invention to provide a spring coiler which is less expensive and less complex than machines heretofore available for supplying springs of two differing firmnesses to an assembly machine in a prescribed sequence.
It has been another objective of this invention to provide a spring coiler which is capable of forming springs at high speeds from two different wires into coil springs capable of being fed directly into a spring assembly machine in a prescribed order.
The coiler of this invention is operative to selectively manufacture coil springs from two different wires, usually one of lighter gauge for making coil springs of relatively light firmness, and a second heavier gauge wire for making more firm coil springs. This machine comprises a pair of opposed feed rollers which are continuously rotatable without interruption in one feed direction during manufacture of coil springs from each of the two different wires and during the changeover from one wire to the other. From the opposed wire feed rollers, the two wires extend into a wire guide from whence the one or the other of the two wires is fed by the opposed feed rollers into a coil forming mechanism. That coil forming mechanism comprises a pair of coil forming tools and at least one pitch determining tool, which coil forming tools are selectively movable into alignment with one or the other of the two different wires, such that one coil forming tool is engageable with and operative to form one wire into the coil, and the other coil forming tool is engageable with and operative to form the other wire into a coil.
The method practiced according to the invention of this invention is operative to form coil springs of differing firmnesses from two different wires. This method comprises the steps of locating the two wires between opposed wire feed rollers, continuously rotating the opposed wire feed rollers without interruption in one wire feed direction, supporting the two wires upon a wire guide positioned adjacent the output side of the wire feed rollers, positioning a first coil forming tool in alignment with the first one of the two wires supported upon the wire guide, moving the rotating opposed feed rollers into driving engagement with a first one of the two wires so as to feed that first wire into engagement with the first coil forming tool, and into engagement with a pitch determining tool so as to create a helically formed coil spring at the end of the first wire, moving the rotating opposed feed rollers out of driving engagement with the first wire to terminate feed of the first wire between the feed rollers, cutting the helically formed coil spring from the end of the first wire, moving a second forming tool into alignment with the second of the two wires supported upon the wire guide, moving the rotating opposed feed rollers into driving engagement with the second wire so as to feed that second wire into engagement with the second coil forming tool and into engagement with a pitch determining tool so as to create a helically formed coil spring at the end of the second wire, moving the opposed feed rollers out of driving engagement with the second wire to terminate feed of that second wire between the opposed feed rollers, and cutting the helically formed coil spring from the end of the second wire.
The principal advantage of the invention of this application is that it provides a very high speed and relatively inexpensive machine for manufacturing coil springs of differing firmnesses from two different wires. Preferably, but not necessarily, the coil springs are of substantially the same dimension, but of differing firmness as a consequence of their having been manufactured from wires of differing diameter.